Chromecast is kind of suspicious device, it always needs a real Internet connection to work. When casting videos from VLC, Chromecast will get also names of the video files. It can be seen eg. in Android (Chromecast) Home app, Chromecast has got the file name of the video file it is viewing. What encrypted net traffic is transferred between Google and Chromecast is unknown. I would assume, it could transfer file names to Alphabet Inc's cloud somewhere for "future development purposes".
I'd like VLC to have option in preferences, when it is casting video files to an any other renderer that "<local>", it would obfuscate or make fake file names, like perhaps timestamp when playing of the video file started.
Like:
UFO_porn_23.mp4 -> 20230119171032.mp4
My_secret_lover_BJ.avi -> 20230119173004.avi
For obvious reasons.